A key GM crop developer, Bayer, has decided to halt UK trials of genetically modified plants. The move is seen as a major blow to the industry. Bayer was the last company carrying out GM trials in the UK, though it said yesterday it hoped to start up again soon when conditions were 'more favourable'.

The company blamed Environment Secretary Margaret Beckett for its decision. Her insistence that the locations of all trial sites be made public had forced its hand, a spokesman told The Observer.

Until last week, Bayer CropScience, Bayer's crop subsidiary. believed it was close to a deal that would allow GM crop test sites - which are regularly destroyed by protesters - to be kept secret. Instead of having to publish exact map references for fields, companies would only have to name the county in which it was holding a trial.

The Advisory Committee on Releases to the Environment had said this vaguer notification was 'acceptable in terms of risk assessment', while the police have always complained that explicit disclosure of test site locations has been a major factor in aiding 'crop-trashers'. But at the last minute the Department of Environment, Food and Rural Affairs (Defra) told Bayer it would not support this change in regulations.

'In the absence of any moves to ensure the security for trials, Bayer CropScience has no choice, therefore, but to cease its variety trial activities in the UK for this coming season,' said the official. 'It is disappointing the criminal activities of a small minority of people have prevented information on GM crop varieties being generated.'

Most GM crop trials carried out over the past few years have been sabotaged, not only those of Bayer. Other companies have pulled out. Now Bayer, the last to continue with them, has decided to call it a day. The current 'brain drain' of UK agricultural scientists to the US and Canada is now only likely to intensify.

The fact that companies also specifically blame Beckett for this latest blow is particularly intriguing. Last week, a letter from Beckett to her fellow Ministers said Britain should back EU laws that ban all GM-free zones, a move that would give the go-ahead to the commercial growing of GM crops here.

But as long as test GM trials are exposed to sabotage, the prospects of commercial growing look remote. 'This is a back-door moratorium,' said an industry source.